Analyses have been made for 871 four-prong events and 463 two-prong events corresponding to multiple pion production, resulting from p−p interactions at 2 Bev in the BNL 20-in. hydrogen bubble chamber. Cross sections have been obtained for all the observable double and triple pion production processes; the branching ratios predicted by the extended isobar model are shown to be in fair agreement with the data, but there are significant differences. The c.m. momentum distributions are also in fair agreement with the predictions of the model, although there are ambiguities in the interpretation. The pion-nucleon Q values give clear evidence for the importance of the (32, 32) resonant state in multiple pion production, but consideration of this state alone does not provide an explanation of the features of double pion production. Some contribution from another state, possibly the I=12 nucleon isobar, is necessary. In double production, the c.m. angular distributions of the nucleons show backward-forward peaking suggestive of a one-pion exchange process. The angular distributions of the nucleons from triple production are almost isotropic.
No description provided.
3600 two-pronged events, obtained in p−p interactions at 2 Bev in the BNL 20-in. hydrogen bubble chamber, have been analyzed. Cross sections have been measured for elastic scattering, for the two modes of single-pion production, p+p→p+n+π+, p+p→p+p+π0, and for strange-particle production. The branching ratio for the two one-pion production reactions is σ(pnπ+)σ(ppπ0)=4.17±0.25. Momentum distributions and Q values indicate that single-pion production proceeds almost entirely through the (32, 32) resonant state. The data have been considered in terms of the extended isobar model and also a one-pion exchange model for production. The branching ratio and momentum distributions can be explained by including a small effect from the I=12 resonant state in addition to the dominant I=32 resonance. The c.m. angular distribution of the nucleons in single-pion production shows very marked backward-forward peaking indicating a one-pion exchange mechanism. Absolute differential cross sections as a function of laboratory kinetic energy have been calculated from Selleri's equation for the pnπ+ reaction. There is good agreement with the data for low four-momentum transfers [q2<0.15(Bev/c)2], but for higher momentum transfers the theoretical cross sections are larger than the experimental cross sections.
No description provided.
Single-pion production in π−−p interactions has been studied at 905, 960, and 1100 MeV. Comparison with the isobar and one-pion-exchange (OPE) mechanisms of pion production shows that, below 1 BeV, pion production occurs primarily through the formation of an intermediate excited state of the nucleon (isobar), while at higher energies the influence of the ρ resonance in the ππ system becomes increasingly important. There is some evidence for an I=2 state in the events at the lower energies.
No description provided.
No description provided.
Meson production in π−p and π+n interactions at 1.7 GeV/c has been studied in two bubble-chamber exposures. Combined results are presented with emphasis on single-pion production (4300 events) which is dominated by the formation of the ρ0 meson in peripheral interactions, and on double-pion production (1100 events) which shows strong formation of the ω meson. These data are compared with the predictions of particle-exchange models, including absorption, and the effects of competing channels are discussed. Evidence for a two-pion decay mode of the ω is examined quantitatively. Processes with higher meson multiplicities are described.
No description provided.
An analysis of the reaction π + n→ ω p in a 6.0 GeV/ c bubble chamber experiment is presented. The production differential cross section and spin density matrix elements are compared with Regge exchange models.
CORRECTED FOR BACKGROUND.
HELICITY FRAME. T-DEPENDENT BACKGROUND SUBTRACTED.
TRANSVERSITY FRAME. T-DEPENDENT BACKGROUND SUBTRACTED.
Backward production of ϱ 0 and f 0 mesons in π + n interactions at 6 GeV/ c is presented. Total and differential cross sections are reported along with spin density matrix elements.
No description provided.
No description provided.
JACKSON (U) FRAME (Z=2).
We present evidence for the decay A20→ωπ+π0 with a branching ratio Γ(A2→ωππ)Γ(A2→ρπ)=0.28±0.09 and for the decay ω(1675)→ωπ+π− with a branching ratio Γ(ω(1975)→ωπ+π−)Γ(ω(1675)→ρπ)=0.47±0.18. Evidence is given for an intermediate B(1235)π state in the ω(1675) decay.
FITTED WITH BREIT-WIGNER RESONANCES PLUS BACKGROUND.
BACKGROUND SUBTRACTED TP DISTRIBUTIONS.
Data are presented on the reactions π + n → ϱ 0 + X and K − p → K ∗0 + X at 6.0 and 7.3 GeV/ c , respectively. Comparisons are made between these two reactions and with other reactions involving inclusive vector meson production at different energies.
No description provided.
No description provided.
No description provided.
Results on K 0 and Λ production in p↑p interactions at 6 GeV are presented. The data are from an exposure of the Argonne 12 ft bubble chamber to a 60% transversely polarized proton beam. Results include data on Λ and K 0 inclusive production, and on the reactions p↑p → p Λ K + (p Σ 0 K + ). The beam asymmetry parameter for p ↑ p → K 0 ( K 0 ) + X is determined to be (−0.52 ± 0.12).
No description provided.
We have studied the reaction p↑p→nΔ++ at 6 GeV/c incident momentum in which the incident protons are 60% transversely polarized. The experiment used the Argonne National Laboratory Zero Gradient Synchrotron polarized beam and the 12-foot hydrogen bubble chamber. We report on about 6000 Δ++ events, with the Δ++ produced in the backward hemisphere in the c.m. system. Spin-density matrix elements as a function of momentum transfer are presented and small beam-polarization-induced effects are described.
BACKWARD-PRODUCED DEL++ HAS HALF THIS CROSS SECTION.
TWO EXPONENTIAL FITS: D(SIG)/DT HAS CHANGE OF SLOPE AT ABOUT -T OF 0.1 GEV**2.
No description provided.
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